It depends on several factors:
1. What is your balance due? Under $10,000? Over $25,000?
2. Who is enforcing collection- ACS or a Revenue Officer?
3. What type of tax is due? Payroll? Income?
4. Are you in an agreement to pay?
5. Do you have assets to pay the liability if sold?
Generally, if you owe over $25,000, a lien will be filed if you are in an agreement or not, no matter what the type of tax owed.
After that, there is no general rule. The IRS will file a lien, under most conditions, (and you do not get a Collection Due Process hearing until after it is filed and the damage is done!) unless you can prove to them that it would ruin your ability to pay the liability (i.e. your job requires that you cannot have a tax lien; i.e. you are a State Revenue Officer- ha!).
The principle is simple. The IRS can act like a secured debt holder. If you had a mortgage or a car loan, you would expect there to be a lien filed by the mortgage holder/lender. Similar is the IRS.
If you have questions on a tax lien, rather than call the IRS and get the standard answer, call a professional tax resolution firm and get the full answer.